Fluid end with non-circular bores and closures for the same

ABSTRACT

A closure element for a fluid end of a reciprocating pump is installable within a segment of a casing of the fluid end to substantially close the segment. The closure element includes a main body that extends from an interior surface to an exterior surface, and at least a portion of the main body has a non-circular cross-sectional shape. A fluid end for the closure element may include a plurality of segments and at least a portion of at least one segment of the plurality of segments may have a non-circular cross-sectional shape configured to receive and secure a closure element with a non-circular cross-sectional shape.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 17/725,929, filed on Apr. 21, 2022, and entitled “Fluid Endwith Non-Circular Bores and Closures For The Same,” the disclosure ofwhich is incorporated by reference in entirety.

FIELD OF INVENTION

The present invention relates to the field of high pressurereciprocating pumps and, in particular, to fluid ends of high pressurereciprocating pumps and closure and/or sealing assemblies for the same.

BACKGROUND

High pressure reciprocating pumps are often used to deliver highpressure fluids during earth drilling operations. One or more sealingarrangements are typically provided in the fluid end to seal conduitsformed in the fluid end and prevent, or at least discourage, leakage.More specifically, the fluid end may define one or more internal pumpingchambers and conduits may define pathways between the one or moreinternal pumping chambers and external surfaces of the fluid end. Atleast some segments of these conduits may be sealed with a closureassembly that may include a closure element (e.g., a cover, plug, and/orsleeve), a seal element, and a retaining element. Alternatively, aclosure assembly may include some subset of these elements. In any case,seals in a fluid end segment may prevent, or at least discourage,leakage through the conduits of a fluid end.

SUMMARY

The present application relates to techniques for closing a segment of afluid end of a high pressure reciprocating pump. The techniques may beembodied as a closure element and/or a closure assembly, either of whichmay be provided independent of any other elements or as part of a fluidend, a kit, and/or a reciprocating pump. Additionally, the techniquesmay be embodied as a fluid end and as a method for closing a segment ofa fluid end of a high pressure reciprocating pump.

More specifically, in accordance with at least one embodiment, thepresent application is directed to a closure element for a fluid end ofa reciprocating pump. The closure element is installable within asegment of a casing of the fluid end to substantially close the segmentand includes a main body that extends from an interior surface to anexterior surface. At least a portion of the main body has a non-circularcross-sectional shape.

Among other advantages, the non-circular shape creates sealing andretaining options that may be advantageous as compared to traditionalsealing and retaining techniques. For example, the closure element maybe self-retaining and/or may be retained within a bore withoutthreading, which is often a high-stress point that is prone to failure.More specifically, closure elements are often secured in a segment witha retaining element that is secured to a fluid end via a threadedconnection formed between threads machined into the fluid end andthreads of the retaining element. These threads are typically subject tohigh levels of cyclical stress and, thus, if the retaining element isnot installed or preloaded correctly, the threads may experience fatiguefailure.

Still further, the non-circular cross-sectional shape allows a sealinglocation to move inwards, adjacent a pumping chamber, or outwards,adjacent an exterior of the fluid end, each of which may provideadditional life span advantages for the closure element and/or the fluidend within which the closure element is installed. For example, aclosure element with a non-circular cross-sectional shape may beretained adjacent the pumping chamber of a fluid end and may protect theinterior edges of a fluid end segment, which are often a point offailure, from wear. Additionally or alternatively, when the closureelement is retained adjacent the pumping chamber or external surface,the closure element can define a corner for a corner seal, which mayavoid traditional pitfalls associated with radial seals (i.e., outerdiameter seals) used on closure elements for fluid ends. For example,when a closure element has a non-circular cross-sectional shape, a boreor corner seal may be used to seal around the closure element. Stillfurther, in some instances, the sealing area can be located on aremovable piece. Then, if the sealing surface becomes damaged (whichtypically happens over time during normal pumping operation), thesealing area can be repaired via a part replacement instead of via aninvasive repair (e.g., a weld repair).

In at least some embodiments, the non-circular cross-sectional shape isan extended ovular shape. This shape may ensure that the closure elementis removable from, but also securable within, a bore segment of a fluidend. Additionally or alternatively, the main body may include a seatingsection proximate the interior surface and a closure section proximatethe exterior surface, one or both of which may have the non-circularcross-sectional shape. For example, the seating section may extendradially beyond the closure section, the seating section may have afirst non-circular cross-sectional shape, and the closure section mayhave a second non-circular cross-sectional shape that is smaller thanthe first non-circular cross-sectional shape. Alternatively, the seatingsection may extend radially beyond the closure section and only one ofthe seating section and the closure section may include the non-circularcross-sectional shape. In either case, the two sections may allow theclosure element to be secured within the fluid end, e.g., against thefluid end and/or a retaining element, and/or to form a corner seal whensecured within a fluid end bore segment.

In at least some instances where the seating section extends radiallybeyond the closure section, the seating section may define anon-circular shoulder between the seating section and the closuresection. In some of these embodiments, the closure section defines aseal channel adjacent or proximate to the non-circular shoulder. Eitherway, this allows some flexibility for the sealing area and may,advantageously, move the sealing area away from locations that are hardto repair. Still further, in some embodiments, the closure elementincludes one or more installation elements disposed on and extendingaway from the exterior surface so that that the one or more installationelements are accessible from an exterior of the segment of the casing ofthe fluid end when the closure element is installed within the segment.Such elements may enable a user to easily install or remove the closureelement from a fluid end bore segment.

In accordance with additional embodiments, the present application isdirected to a closure assembly. The closure assembly may be formed withthe foregoing closure element embodiments, as well as variationsthereof. Thus, the closure assembly may realize any of the foregoingadvantages. Additionally, the closure assembly may include a retainingassembly that is coupleable to the exterior surface of the closureelement. Generally, the retaining assembly may prevent, or at leastdiscourage, the closure element from being blown out (i.e., removed) ofa bore segment, e.g., by pressure in a pumping chamber. In someembodiments, the retaining assembly may also prevent, or at leastdiscourage, the closure element from being sucked into a pumping chamberof the fluid end (e.g., during an intake stroke of a reciprocatingcomponent operating in or adjacent the fluid end).

In at least some embodiments, the retaining assembly also includescouplers that removably couple a retaining element to the closureelement. Additionally or alternatively, the retaining assembly may beconfigured to be disposed entirely within the segment of the casing ofthe fluid end when the closure element is installed within the segmentof the casing of the fluid end. In fact, in such embodiments, theretaining assembly may appear to be part of the closure element and,thus, such embodiments may sometimes be referred to as “two-part closureelement” embodiments. Among other advantages, such embodiments may allowa closure element to seal adjacent a pumping chamber, potentiallyreducing the size of the pumping chamber, which is advantageous forpumping compressible fluids. Additionally or alternatively, a retainingassembly disposed within a fluid end bore may reduce the overallfootprint of a fluid end (since the retaining assembly does not extendtherefrom), potentially reducing snag/trip hazards around the fluid end(e.g., as compared to retaining assemblies that protrude from a fluidend).

Alternatively, in some instances, at least a portion of the retainingassembly is configured to be disposed at least partially exteriorly ofthe casing of the fluid end when the closure element is installed withinthe segment of the casing of the fluid end. For example, the retainingassembly may include a retainer, such as an annular retaining ring witha non-circular cross section, disposed exteriorly of the casing of thefluid end. The retainer can define a seat on which a shoulder of theportion of the main body of the closure element with the non-circularcross-sectional shape may sit. Then, the sealing area for the closureelement may be formed against this annular ring, which can be easilyrepaired or replaced (e.g., without invasive repairs). Moreover, in atleast some embodiments, the retainer may be secured to a fluid end witha plurality of couplers, but need not be removed to replace the closureelement. Instead, the non-circular cross-sectional shape of the closureelement may allow the closure element to be replaced or servicedquickly, without removing plurality of couplers (e.g., by rotating theclosure element into an installation/removal orientation while theretainer remains in place).

In accordance with additional embodiments, the present application isdirected to a fluid end of a reciprocating pump including a casing withintersecting conduits that collectively define a plurality of segmentsextending from an external surface of the casing to a pumping chamberdefined within the casing. At least a portion of at least one segment ofthe plurality of segments has a non-circular cross-sectional shapeconfigured to receive and secure a closure element with a non-circularcross-sectional shape. At least because of the non-circularcross-sectional shape, this fluid end may realize many of the advantagesdiscussed above in connection with the closure elements and/or theclosure assemblies presented herein.

In some embodiments, the plurality of segments include an intake segmentthat provides a fluid inlet for the pumping chamber, a discharge segmentthat that provides a fluid outlet for the pumping chamber, areciprocation segment, and an access segment. The reciprocation segmentis configured to operably couple a reciprocating component to thepumping chamber so that the reciprocating component can draw fluid intothe pumping chamber via the intake segment and discharge fluid from thepumping chamber via the discharge segment. The access segment providesaccess to at least the pumping chamber. In some instances, the accesssegment has the non-circular cross-sectional shape. Additionally oralternatively, the discharge segment may have the non-circularcross-sectional shape.

Regardless of the segments included in a fluid end, the portion of theat least one segment of the plurality of segments that has thenon-circular cross-sectional shape may comprise a segment portionadjacent to the pumping chamber. Alternatively, the portion of the atleast one segment of the plurality of segments that has the non-circularcross-sectional shape may comprise a segment portion adjacent to theexternal surface of the casing.

In accordance with additional embodiments, the present application isdirected to a method of closing an externally open segment of a fluidend of a reciprocating pump with a closure assembly. The method includesinserting a non-circular closure element into a segment of a fluidcasing in a first direction while the non-circular closure element isdisposed in a first orientation. Then, the non-circular closure elementis rotated to a second orientation that is angularly offset from thefirst orientation with respect to at least one axis of rotation. Afterand/or during the rotation, the non-circular closure element is movedwithin the segment of a fluid casing in a second direction. The seconddirection is opposite the first direction and, thus, causes thenon-circular closure element to seat within the segment. In some ofthese embodiments, the rotating occurs in a pumping chamber of the fluidend and involves a first rotation of approximately ninety degrees abouta first axis of rotation and a second rotation of approximately ninetydegrees about a second axis of rotation.

Notably, among other advantages, the closure element can be seated intoa bore segment without a retaining element and/or without threading. Atleast because this method utilizes a non-circular closure element, thismethod may also realize any advantages described above. This method mayalso be executed with any variations of closure elements or closureassemblies described herein.

The foregoing advantages and features will become evident in view of thedrawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

To complete the description and in order to provide for a betterunderstanding of the present application, a set of drawings is provided.The drawings form an integral part of the description and illustrateembodiments of the present application, which should not be interpretedas restricting the scope of the invention, but just as examples. Thedrawings comprise the following figures:

FIG. 1 is a perspective view of a prior art reciprocating pump includinga fluid end.

FIG. 2 is a cross sectional view of another prior art fluid end.

FIG. 3 is a front view of a fluid end with a non-circular bore that hasnon-circular closure assemblies installed therein. The fluid end andclosure assemblies are each formed according to example embodiments ofthe present application.

FIG. 4 is a side, sectional view of the fluid end of FIG. 3 taken alongline “A-A” of FIG. 3 .

FIG. 5 is a perspective view of one of the closure assemblies installedin the fluid end of FIGS. 3 and 4 .

FIG. 6 is a front, sectional view of the fluid end of FIG. 3 taken alongline “A-A” of FIG. 4 , with the closure assembly removed from the fluidend.

FIG. 7 is a detail view of a portion of the sectional view of FIG. 4with the closure assembly removed from the fluid end.

FIG. 8A is a detail view of portion “B” of the sectional view of FIG. 4.

FIG. 8B is a front perspective view of a retaining element that may beused with at least a closure element of the closure assembly of FIG. 3 ,according to an example embodiment.

FIG. 8C is a schematic, sectional view of the retaining element of FIG.8B while installed on the closure element of the closure assembly ofFIG. 3 .

FIG. 8D is a front perspective view of another example embodiment of aclosure element that may be used with at least a retaining element ofthe closure assembly of FIG. 3 .

FIG. 8E is a rear perspective view of the closure element of FIG. 8D.

FIG. 8F is a side, sectional view of the closure element of FIG. 8D,taken along line A-A of FIG. 8E.

FIG. 8G is a front perspective view of yet another example embodiment ofa closure element that may be used with at least a retaining element ofthe closure assembly of FIG. 3 .

FIG. 8H is a side perspective view of the closure element of FIG. 8Gassembled with a retaining element to form at least a portion of aclosure assembly.

FIG. 8I is a schematic, front sectional view of a fluid end embodimentwith the closure assembly removed from the fluid end.

FIG. 9 is a side, sectional view of a portion of another exampleembodiment of a fluid end with a non-circular bore formed in accordancewith the present application.

FIG. 10 is a perspective view of a second embodiment of a closureassembly formed in accordance with the present application.

FIG. 11A is a front view of a portion of the fluid end of FIG. 3 with athird embodiment of the closure assembly presented herein installedtherein.

FIG. 11B is a side, sectional view of the fluid end and closure assemblyof FIG. 11A.

FIG. 12A is a front view of a portion of the fluid end of FIG. 3 with avariation of the third embodiment of the closure assembly presentedherein installed therein.

FIG. 12B is a side, sectional view of the fluid end and closure assemblyof FIG. 12A.

FIG. 13 is a side, sectional view of another example embodiment of afluid end with a non-circular bore including a fourth embodiment of theclosure assembly installed therein. The fluid end and closure assemblyare each formed according to example embodiments of the presentapplication.

FIG. 14 is a perspective view of the closure assembly shown in FIG. 13 .

FIG. 15 is a detail view of portion “B” of the sectional view of FIG. 13.

FIG. 16A is a side perspective, sectional view of yet another exampleembodiment of a fluid end with a non-circular bore including a fifthembodiment of the closure assembly presented herein installed therein.The fluid end and closure assembly are each formed according to exampleembodiments of the present application.

FIG. 16B is a front view of the fluid end of FIG. 16A, with a closureelement of the closure assembly for the fluid end being shown in aninstallation orientation.

FIG. 17A is a front perspective view of yet another example embodimentof a fluid end with a non-circular bore including a variant of the fifthembodiment of the closure assembly presented herein installed therein.The fluid end and closure assembly are each formed according to exampleembodiments of the present application.

FIG. 17B is a sectional view of the fluid end and closure assembly ofFIG. 17A taken along line A-A of FIG. 17A.

FIGS. 18A-18E depict a method of closing an externally open segment of afluid end of a reciprocating pump with a non-circular closure assembly,according to an example embodiment of the present application.

FIG. 19 depicts a final assembly formed when executing the method ofFIGS. 18A-18E in accordance with an example embodiment of the presentapplication.

Like reference numerals have been used to identify like elementsthroughout this disclosure.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense but isgiven solely for the purpose of describing the broad principles of theinvention. Embodiments of the invention will be described by way ofexample, with reference to the above-mentioned drawings showing elementsand results according to the present invention.

Generally, the present application is directed to a fluid end of areciprocating pump, closure assemblies for the fluid end, and/orportions thereof. The fluid end presented herein has at least one borewith a non-circular cross-sectional shape while the closure assembliespresented herein include least some components or sections withnon-circular cross-sectional shapes. Typically, fluid ends forreciprocating pumps have bores with circular cross-sectional shapes(e.g., cylindrical bores) while closure elements therefor (e.g., valvecovers, plugs, sleeves, etc.) have corresponding circular/cylindricalshapes to allow the closure elements to close and/or seal the bore.

These circular/cylindrical closure elements are typically secured in abore segment with a threaded retaining element that engages threadsmachined into the fluid end. Such an arrangement creates at least twoissues. First, a cylindrical closure element secured in a cylindricalbore can define sealing areas on the inner surface of the bore. Thissurface is often defined by the fluid end and, thus, can be verydifficult to repair (e.g., repair may require an invasive weld repair).Second, with such an arrangement, the threads on the retaining elementare subject to high levels of cyclical stress. Thus, if the retainingelement is not preloaded correctly, the threads may experience fatiguefailure.

The closure assemblies and/or the fluid end presented herein resolvethese issues and, thus, can extend the lifespan of both the fluid endand the closure element. Initially, in at least some embodiments, aclosure element with a non-circular cross-sectional shape can be securedwithin a fluid end bore without a threaded retaining element, therebyeliminating a potential point of failure. Instead, the closure elementcan be retained directly on a fluid end and/or on a retaining elementthat is fixed in place on a fluid end (e.g., the retaining element neednot be removed for installation or removal of the closure element). Thismay also make the closure assembly easy to install, decreasing theamount of time required for installation and/or removal which, in turn,decreases downtime. Moreover, in at least some embodiments where a sealdisposed around a closure element seals against a retaining element, thefluid end will not define a sealing area and, thus, will not experiencewear associated with the sealing area. Additionally or alternatively,the non-circular cross-sectional shapes of the present application mayallow the seals to be/provide bore or corner seals, which may be morerobust than radial seals (e.g., seals between nested components ofdifferent radial dimensions).

Now referring to FIG. 1 for a description of a prior art reciprocatingpump 100. The reciprocating pump 100 includes a power end 102 and afluid end 104. The power end 102 includes a crankshaft that drives aplurality of reciprocating plungers within the fluid end 104 to pumpfluid at high pressure. Generally, the power end 102 is capable ofgenerating forces sufficient to cause the fluid end 104 to deliver highpressure fluids to earth drilling operations. For example, the power end102 may be configured to support hydraulic fracturing (i.e., fracking)operations, where fracking liquid (e.g., a mixture of water and sand) isinjected into rock formations at high pressures to allow natural oil andgas to be extracted from the rock formations. However, to be clear, thisexample is not intended to be limiting and the present application maybe applicable to both fracking and drilling operations.

Often, the reciprocating pump 100 may be quite large and may, forexample, be supported by a semi-tractor truck (“semi”) that can move thereciprocating pump 100 to and from a well. Specifically, in someinstances, a semi may move the reciprocating pump 100 off a well whenthe reciprocating pump 100 requires maintenance. However, areciprocating pump 100 is typically moved off a well only when areplacement pump (and an associated semi) is available to move intoplace at the well, which may be rare. Thus, often, the reciprocatingpump is taken offline at a well and maintenance is performed while thereciprocating pump 100 remains on the well. If not for this maintenance,the reciprocating pump 100 could operate continuously to extract naturaloil and gas (or conduct any other operation). Consequently, anyimprovements that extend the lifespan of components of the reciprocatingpump 100, especially typical “wear” components, and extend the timebetween maintenance operations (i.e., between downtime) are highlydesirable.

Still referring to FIG. 1 , but now in combination with FIG. 2 , invarious embodiments, the fluid end 104 may be shaped differently and/orhave different features, but may still generally perform the samefunctions, define similar structures, and house similar components. Toillustrate potential shape variations, FIG. 2 shows a side, sectionalview of a fluid end 104′ with different internal and external shaping ascompared to fluid end 104. However, since fluid end 104 and fluid end104′ have many operational similarities, FIGS. 1 and 2 are labeled withthe same reference numerals and are both described with respect to thesecommon reference labels.

The sectional view of FIG. 2 is taken along a central or plunger axis ofone of the plungers 202 included in a reciprocating pump 100. Thus,although FIG. 2 depicts a single pumping chamber 208, it should beunderstood that a fluid end 104 can include multiple pumping chambers208 arranged side-by-side. In fact, in at least some embodiments (e.g.,the embodiment of FIG. 1 ), a casing 206 of the fluid end 104 forms aplurality of pumping chambers 208 and each chamber 208 includes aplunger 202 that reciprocates within the casing 206. However,side-by-side pumping chambers 208 need not be defined by a single casing206. For example, in some embodiments, the fluid end 104 may be modularand different casing segments may house one or more pumping chambers208. In any case, the one or more pumping chambers 208 are arrangedside-by-side so that corresponding conduits are positioned adjacent eachother and generate substantially parallel pumping action. Specifically,with each stroke of the plunger 202, low pressure fluid is drawn intothe pumping chamber 208 and high pressure fluid is discharged. But,often, the fluid within the pumping chamber 208 contains abrasivematerial (i.e., “debris”) that can damage seals formed in thereciprocating pump 100.

As can be seen in FIG. 2 , the pumping paths and pumping chamber 208 ofthe fluid end 104 are formed by conduits that extend through the casing206 to define openings at an external surface 210 of the casing 206.More specifically, a first conduit 212 extends longitudinally (e.g.,vertically) through the casing 206 while a second conduit 222 extendslaterally (e.g., horizontally) through the casing 206. Thus, conduit 212intersects conduit 222 to at least partially (and collectively) definethe pumping chamber 208. In the prior art fluid end 104 and prior artfluid end 104′, conduits 212 and 222 are substantially cylindrical, butthe diameters of conduit 212 and conduit 222 may vary throughout thecasing 206 so that conduits 212 and 222 can receive various structures,such as sealing assemblies or components thereof.

Regardless of the diameters of conduit 212 and conduit 222, each conduitmay include two segments, each of which extend from the pumping chamber208 to the external surface 210 of the casing 206. Specifically, conduit212 includes a first segment 2124 and a second segment 2126 that opposesthe first segment 2124. Likewise, conduit 222 includes a third segment2224 and a fourth segment 2226 that opposes the third segment 2224. Inthe depicted embodiment, the segments of a conduit (e.g., segments 2124and 2126 or segments 2224 and 2226) are substantially coaxial while thesegments of different conduits are substantially orthogonal. However, inother embodiments, segments 2124, 2126, 2224, and 2226 may be arrangedalong any desired angle or angles, for example, to intersect pumpingchamber 208 at one or more non-straight angles.

In the depicted embodiment, conduit 212 defines a fluid path through thefluid end 104. Segment 2126 is an intake segment that connects thepumping chamber to a piping system 106 delivering fluid to the fluid end104. Meanwhile, segment 2124 is an outlet or discharge segment thatallows compressed fluid to exit the fluid end 104. Thus, in operation,segments 2126 and 2124 may include valve components 51 and 52,respectively, (e.g., one-way valves) that allow segments 2126 and 2124to selectively open. Typically, valve components 51 in the inlet segment2126 may be secured therein by a piping system 106. Meanwhile valvecomponents 52 in outlet segment 2124 may be secured therein by a closureassembly 53 that, in the prior art example depicted in FIG. 2 , includesa closure element 251 (also referred to as a discharge plug) that issecured in the segment 2124 by a retaining assembly 252. Notably, theprior art retaining assembly 252 is coupled to segment 2124 via threads2128 defined by an interior wall of segment 2124.

On the other hand, segment 2226 defines, at least in part, a cylinderfor plunger 202, and/or connects the casing 206 to a cylinder forplunger 202. For example, in the depicted embodiment, a casing segment35 is secured to segment 2226 and houses a packing assembly 36configured to seal against a plunger 202 disposed interiorly of thepacking assembly 36. In any case, reciprocation of a plunger 202 in oradjacent to segment 2226, which may be referred to as a reciprocationsegment, draws fluid into the pumping chamber 208 via inlet segment 2126and pumps the fluid out of the pumping chamber 208 via outlet segment2124. Notably, in the depicted prior art arrangement, the packingassembly 36 is retained within casing segment 35 with a retainingelement 37 that is threadably coupled to casing segment 35.

Segment 2224 is an access segment that can be opened to access to partsdisposed within casing 206 and/or surfaces defined within casing 206.During operation, access segment 2224 may be closed by a closureassembly 54 that, in the prior art example depicted in FIG. 2 , includesa closure element 254 (also referred to as a suction plug) that issecured in the segment 2224 by a retaining assembly 256. Notably, theprior art retaining assembly 256 is coupled to segment 2224 via threads2228 defined by an interior wall of segment 2224. However, in someembodiments, conduit 222 need not include segment 2224 and conduit 222may be formed from a single segment (segment 2226) that extends from thepumping chamber 208 to the external surface 210 of casing 206.

Overall, in operation, fluid may enter fluid end 104 (or fluid end 104′)via multiple openings, as represented by opening 216 in FIG. 2 , andexit fluid end 104 (or fluid end 104′) via multiple openings, asrepresented by opening 214 in FIG. 2 . In at least some embodiments,fluid enters openings 216 via pipes of piping system 106, flows throughpumping chamber 208 (due to reciprocation of a plunger 202), and thenflows through openings 214 into a channel 108. However, piping system106 and channel 108 are merely example conduits and, in variousembodiments, fluid end 104 may receive and discharge fluid via anynumber of pipes and/or conduits, along pathways of any desirable size orshape.

Also, during operation of pump 100, the first segment 2124 (of conduit212), the third segment 2224 (of conduit 222), and the fourth segment2226 (of conduit 222) may each be “closed” segments. By comparison, thesecond segment 2126 (of conduit 212) may be an “open” segment thatallows fluid to flow from the external surface 210 to the pumpingchamber 208. That is, for the purposes of this application, a “closed”segment may prevent, or at least substantially prevent, direct fluidflow between the pumping chamber 208 and the external surface 210 of thecasing 206 while an “open” segment may allow fluid flow between thepumping chamber 208 and the external surface 210. To be clear, “directfluid flow” requires flow along only the segment so that, for example,fluid flowing from pumping chamber 208 to the external surface 210 alongsegment 2124 and channel 108 does not flow directly to the externalsurface 210 via segment 2124.

Now turning to FIGS. 3 and 4 , these Figures depict a front view and aside, sectional view, respectively, of an example embodiment of a fluidend 304 formed in accordance with the present application. Additionally,in these Figures, an example embodiment of a closure assembly 400 formedin accordance with the present application is shown installed in thefluid end 304. For simplicity and clarity, these Figures continue to usesome reference numerals from the prior art illustrated in FIGS. 1 and 2; however, such continuity should not be construed as limiting in anymanner and, instead, is only utilized for ease of understanding.

In fact, FIGS. 3 and 4 should not be construed as limiting in anymanner. For example, while FIGS. 3 and 4 depict a fluid end 304 withnon-circular access segments 3224 that are sealed by non-circularclosure assemblies 400, any desirable segments of a fluid end formed inaccordance with the present application may be non-circular. That is,segments 2124, 2126, and/or 2226 could be non-circular, either inaddition to or instead of non-circular access segments 3224.Additionally or alternatively, only some segments of a particular typeof segment could be non-circular (e.g., a subset of the access segments3224 depicted in FIGS. 3 and 4 ). Still further, while FIGS. 3 and 4only depict closure assemblies 400 in non-circular access segments 3224,as mentioned, in operation, segment 2124, segment 3224, and segment 2226are each be completely capped, sealed, plugged, or otherwise closed toprevent fluid from passing through one of these segments to the externalsurface 310 of casing 306.

Still referring to FIGS. 3 and 4 , but now in combination with FIG. 5 ,the closure assembly 400 depicted in these Figures includes at least asealing assembly 401 formed by a closure element 402 and a seal 461and/or seal assembly 460 (e.g., a seal 461 and a seal carrier 462). Insome embodiments (an example of which is described below), the sealingassembly 401 is self-retaining and, thus, can be installed within anon-circular segment 3224 without any additional components. However, inthe embodiment depicted in FIGS. 3-5 , the closure assembly 400 alsoincludes a retaining assembly 470 that retains the assembly 401 within anon-circular segment 3224. More specifically, the retaining assembly 470is removably coupleable to the closure element 402 and, when coupledthereto, retains the seal 461 adjacent the closure element 402. However,the retaining assembly 470 may also serve to retain the closure element402 within the non-circular segment 3224. For example, in someembodiments, the retaining assembly 470 may retain the closure element402 in the non-circular segment 3224 when a suction stroke of areciprocating component (e.g., plunger 202) urges the closure element402 into the pumping chamber 308 of the fluid end 304.

As can be seen in FIGS. 4 and 5 , the closure element 402 includes amain body that extends from an interior surface 406 to an exteriorsurface 410. When the closure element 402 is installed in thenon-circular segment 3224, the interior surface 406 is disposed closerto the pumping chamber 308 than the exterior surface 410. That is, theinterior surface 406 may be “upstream” (i.e., closer to the pumpingchamber 308) of the exterior surface 410. Or, from another perspective,the exterior surface 410 may be “downstream” of the interior surface406. In fact, in the particular embodiment of at least FIGS. 3-5 , theinterior surface 406 of the closure element 402 is disposed in oradjacent to the pumping chamber 308 when the closure element 402 isinstalled in the non-circular segment 3224. This position may beadvantageous not only because it allows the closure assembly 400 to besecured in place without threads, but also because it reduces theoverall size of the pumping chamber 308, which is typically advantageouswhen pumping compressible fluids (i.e., fluids for which thereciprocating pump 100 is intended). To help smooth pressure gradientsacross the interior surface 406 (e.g., created by fluid moving throughthe pumping chamber 308), the interior surface 406 may include taperededges 408.

It is possible to install the closure element 402 in or adjacent thepumping chamber 308 because the overall shape (e.g., the largestdimension) of the closure element 402 is non-circular so that theclosure element 402 has an elongated overall dimension 442 and a narrowoverall dimension 444, which is smaller than the elongated overalldimension 442. As is described in detail below, dimensions 442 and 444allow the closure element 402 to be easily inserted into and seatedagainst a non-circular portion of the non-circular segment 3224.

The features of the closure element 402 also facilitate this positioningand installation. More specifically, moving from the exterior surface410 to the interior surface 406, the closure element 402 includes aclosure section 430 and a seating section 438. That is, the closureelement 402 includes a closure section 430 adjacent, or at leastproximate, to the exterior surface 410 and a seating section 438adjacent, or at least proximate, to the interior surface 406. Theseating section 438 extends radially beyond the closure section 430 and,thus, defines a shoulder 436 between the closure section 430 and theseating section 438. As is described in further detail below, shoulder436 can engage (e.g. sit on) a seat of the non-circular segment 3224 tosecure, or at least orient/align, the closure element 402 within thenon-circular segment 3224.

In the depicted embodiment, the closure section 430 has a radial surface432 that has a non-circular cross-sectional shape. Similarly, theseating section 438 has a radial surface 439 that has a non-circularcross-sectional shape. In fact, the radial surface 439 of the seatingsection 438 and the radial surface 432 of the closure section 430 havenon-circular cross-sectional shapes that are substantially the same.That is, the closure section 430 has a first non-circularcross-sectional shape and the seating section 438 has a secondnon-circular cross-sectional shape that is smaller than, but similarlyproportioned to, the first non-circular cross-sectional shape.Consequently, the closure section 430 and the seating section 438 definea shoulder 436 with a face 437 of substantially constant width and ofsubstantially the same shape as the radial surface 439 and the radialsurface 432. In the depicted embodiment, the non-circular shape of thesevarious sections or features is an elongated oval, insofar as “elongatedoval” or variations thereof, such as “elongated ovular shape,” are usedto denote a shape formed from two semi-circular lines connected bystraight lines. However, this is just an example and other non-circularshapes, including one or more ellipses, can be used to achieve anon-circular shape.

In fact, all of the depicted shaping and dimensioning is provided as anexample and other embodiments need not have such dimensions and/orshaping. Instead, the closure element 402, and the overall assembly 401,should have dimensions and shaping that correspond with the dimensionsand shaping of the non-circular segment 3224. For example, in someembodiments, the seating section 438 might have a non-circular shape andthe closure section 430 might have a different non-circular shape oreven a circular shape. In fact, in some embodiments, it may beadvantageous to have a circular closure section 430. This is becausemachining non-circular shapes may be more difficult than machiningcircular shapes. When the closure element 402 includes a circularclosure section 430, the non-circular segment 3224 may also include acorresponding circular section. Consequently, a circular closure section430 may decrease the amount of complex machining required to manufacturethe closure element 402 and non-circular segment 3224, which may lowerthe costs associated with manufacturing the fluid end 304 and theclosure assembly 400 presented herein.

However, to preserve the advantages of the non-circular overall shape ofthe closure assembly 400, when the closure section 430 has a circularshape or a non-circular shape that differs from the non-circular shapeof the seating section 438, the overall dimensions of the closuresection 430 should not extend beyond the narrow overall dimension 444 ofthe closure element 402. Any extension beyond the narrow overalldimension 444 might restrict or prevent the closure element 402 frombeing installed in the non-circular segment 3224. In any case, if onlyone of the closure section 430 and the seating section 438 includes anon-circular cross-sectional shape, the shoulder 436 may have adifferent shape than both of these sections. This is because an innerboundary of the shoulder 436 is defined by the closure section 430 andthe outer boundary of the shoulder 436 is defined by the seating section438.

Still referring to FIGS. 4 and 5 , in this embodiment, the closureassembly 400 includes a retaining assembly 470 that is coupled directedto the exterior surface 410 of the closure element 402 and inserted intothe non-circular segment 3224 with the closure element 402. That is, theretaining assembly 470, which includes a retaining element 472 andcouplers 495, is configured to be disposed entirely within thenon-circular segment 3224 of the casing 306 of the fluid end 304 whenthe closure element 402 is installed within the non-circular segment3224 to substantially close the non-circular segment 3224. Accordingly,the exterior surface 410 includes a variety of features to securelymount and couple the retaining assembly 470 to the closure element 402.

Specifically, the exterior surface 410 includes a central protrusion 414that defines a bore 416 and that is surrounded by a plurality ofreceivers 412 (e.g., bores). Correspondingly, the retaining element 472,which extends from an interior surface 474 to an exterior surface 476,defines bores 478 configured to align with the receivers 412 and acentral bore 479 that aligns with the protrusion 414. As can be seen,the bores 478 of the depicted embodiment are countersunk to minimize thedistance that couplers 495 installed therein extend beyond the exteriorsurface 476. Meanwhile, the central bore 479 can sit on the protrusion414 of the closure element 402 to center the retaining element 472 onthe exterior surface 410 of the closure element 402 while the couplers495 are installed through bores 478 and into receivers 412.

In at least some embodiments, the closure element 402 has a firstsurface hardness and the retaining assembly 470, or at least portionsthereof, such as a retaining element 472 of the retaining assembly 470,have a second surface hardness that is less hard than the first surfacehardness. The increased hardness of the closure element 402 will respondto higher loads between the closure element 402 and the fluid end 304during pumping operations and, thus, will prolong the life of a closureassembly including the closure element 402. However, the entire closureelement 402 need not have this increased hardness and, for example, theinterior surface 406 and/or tapered edges 408 might have increasedhardness as compared to a remainder of the closure element 402. Forexample, the closure element 402 might have a coating on the taperededges 408 to provide the increased hardness. In some instances, thecoating might provide corrosion resistance, friction resistance, and/orimproved sealing, either instead of or in addition to providingincreased hardness. Moreover, in some embodiments, the inner wall of thefluid end bore, or at least a portion thereof, may be coated with such acoating, perhaps instead of coating the closure element 402.

Still referring to FIGS. 4 and 5 , but now in combination with FIG. 8A,perhaps the most important aspect of the retaining assembly 470 is thatthe interior surface 474 of the retaining element 472 bounds a channel434 defined by the closure section 430 when the retaining assembly 470is installed on the closure element 402. More specifically, in thedepicted embodiment, when the retaining assembly 470 is coupled to theclosure element 402, the seating section 438 provides an upstream wallof a channel 434 and the interior surface 474 of the retaining assembly470 provides a downstream wall for channel 434. Thus, coupling theretaining assembly 470 to the closure element 402 may retain or secure aseal 461, either alone or with a seal carrier 462 (i.e., a spacer),within channel 434, as is shown best in FIG. 8A. In differentembodiments, different seals 461 and/or seal carriers 462 may beutilized to extend the lifespan of the closure assembly 400 and/or thefluid end within which it is installed.

Notably, in the depicted embodiment, the seal carrier 462 may bepositioned upstream of the seal 461 (such an arrangement is alsoillustrated in FIGS. 8C and 8H). Additionally, the seal carrier 462 maybe a single-piece element (again, such an arrangement is alsoillustrated in FIGS. 8C and 8H). This arrangement and single piececonstruction may provide sturdy support for the seal 461, which mayimprove and/or maintain seal integrity during installation and/or duringpumping operations. That is, the seal carrier 462 may backstop the seal461 and serve as an upstream gland wall for the seal 461 during pumpingoperations. Testing has found that installing a sealing assembly 401(i.e., a closure element 402 and a seal assembly 460) without a sealcarrier 462 can sometimes cause the seal 461 to warp and/or twist. Forexample, rolling forces created by translating the seal 461 along anon-circular segment 3224 may twist or warp the seal 461 if the seal 461is not supported by a seal carrier 462. Thus, the seal carrier 462 mayhelp ensure the sealing assembly 401 is properly installed in anon-circular segment 3224.

FIGS. 8B and 8C illustrate another embodiment of a retaining element472′ that may be used to form another embodiment of a retaining assembly470′. The retaining assembly 470′ may operate and/or function in asimilar manner to retaining assembly 470. Thus, retaining element 472′and retaining element 472 are labeled with many like reference numeralsand, for brevity, the description of retaining element 472′ includedherein focuses on differences between the two embodiments. For example,retaining element 472′ is similar to retaining element 472 because itextends from an interior surface 474 to an exterior surface 476 andincludes bores 478 and a central bore 479. Thus, any description ofthese parts included herein should be understood to apply to retainingelement 472′. In contrast, retaining element 472′ includes variousfeatures that allow a flexible installation elements 485 to be coupledto the closure assembly 400′.

More specifically, the retaining element 472′ includes holes 481 thatextend from the interior surface 474 to the exterior surface 476, orvice versa, so that flexible installation elements 485 can be installedthrough a main body of the retaining element 472′. Additionally, aconnecting passageway 482 is formed on the interior surface 474. Theconnecting passageway 482 allows a single flexible installation element485 to be fed through two holes 481 while also extending across aportion of the interior surface 474. This creates a leverage or grippoint that a user can use to manipulate the closure assembly 400′, e.g.,during installation of the closure assembly 400′ into a fluid end 304.Also, the connecting passageway 482 allows the flexible installationelements 485 to extend along the interior surface 474 without protrudingtherefrom. Thus, the flexible installation elements 485 will not impactthe interface between the interior surface 474 of the retaining assembly470′ and the exterior surface 410 of the closure element 402 whencouplers 495 couple the retaining assembly 470′ to the closure element402 (e.g., to secure a seal 461 and seal carrier 462 in placetherebetween). This placement also ensures that the flexibleinstallation elements 485 do not wear, change the geometry, or otherwisenegatively affect the closure element 402 while still enabling easyinstallation and/or removal of the flexible installation elements 485.

With the holes 481 and connecting passageway 482, the flexibleinstallation elements 485 may be installed onto a retaining element 472′prior to coupling the retaining element 472′ to a closure element 402,while the interior surface 474 of the retaining element 472′ is stilleasily accessible. The flexible installation elements 485 can be fedthrough one hole 481, routed to a second hole 481 via the connectingpassageway 482, and fed back out of the retaining element 472′ via thesecond hole. Then, retaining element 472′ can be coupled to closureelement 402 while the flexible installation elements 485 are disposedbetween the retaining element 472′ and the closure element 402.

In the depicted embodiment, the retaining element 472′ includes twopairs of holes 481 and each pair of holes 481 is connected by aconnecting passageway 482. The pairs of holes 481 are located above andbelow the central bore 479, but within the elongated, ovular arrangementof bores 478. In other embodiments, the holes 481 and/or connectingpassageway 482 may be disposed in any desirable location. In fact, inother embodiments, the closure element 402 need not include holes 481and may include any other features that allow flexible handles 485 tothe closure element, such as eye bolts, connected blind holes, etc.However, regardless of how the flexible handles 485 are coupled to theclosure element 402, it may be beneficial to arrange flexible handles485 symmetrically and/or evenly with respect to a center of theretaining element 472′ (e.g., around and/or with respect to bore 479)because symmetrically or evenly spaced flexible installation elements485 may allow for linear translation that avoids tilting or rotation.

Additionally, in the depicted embodiment, the flexible installationelements 485 are wires, but other embodiments may utilize any elongate,flexible material as flexible installation elements 485. In any case,the flexible installation elements 485 will allow a user/operator tomanipulate the retaining assembly 470′ from a location that is exteriorof the fluid end 304. This, in turn, reduces the amount of time thatoperators will need to have their hands inside of a non-circular segment3224 of the fluid end 304. In some instances, the flexible installationelements 485 may also make it easier for an operator/user to retrievethe retaining assembly 470′ and/or closure assembly 400′ if theretaining assembly 470′ and/or closure assembly 400′ falls into anunwanted location, such as into the pumping chamber 308.

FIGS. 8D, 8E, and 8F illustrate another embodiment of a closure element420 that may be used to form a closure assembly. The closure element 420may operate and/or function in a similar manner to closure element 402.Thus, closure element 420 and closure element 402 are labeled with manylike reference numerals and, for brevity, the description of closureelement 420 included herein focuses on differences between the twoembodiments. Perhaps the most notable difference is that a pressurerelief conduit 423 extends through closure element 420. Otherwise,closure element 420 extends from an interior surface 406 to an exteriorsurface 410 that has receivers 412 and a protrusion 414 with a bore 416,like closure element 402, and also has a seating section 438 and closuresection 430 like closure element 402.

In the depicted embodiment, the pressure relief conduit 423 is apassageway that extends through the main body of the closure element420, initiating at entrance 421 and terminating at exit 422. Theentrance 421 is disposed on the interior surface 406 and the exit 422 isdisposed on the radial surface 432 of the closure section 430,intersecting the channel 434 of the closure section 430 that receives aseal assembly. More specifically, in the depicted embodiment the exit422 is configured to intersect the channel 434 at a location that isupstream (e.g. closer to a pumping chamber) of a seal 461 positioned inchannel 434. Thus, fluid flowing through the pressure relief conduit 423may enter the channel 434 but the seal 461 will prevent the fluid frombypassing the closure element 420 to exit the segment. Alternatively,the closure element 420 and/or a retaining assembly coupled theretomight include other sealing features that ensure fluid exiting thepressure relief conduit 423 at exit 422 does not escape a fluid endsegment in which the closure element 420 is installed. In any case, thepressure relief conduit 423 will not prevent the closure element 420from closing a segment in which it is installed.

Overall, the pressure relief conduit 423 provides a flow path alongwhich fluid may flow past the seating section 438 without contacting thetapered edges 408 of the interior surface 406 or the shoulder 436defined by the seating section 438. This prevents, or at leastdiscourages, high pressure fluid from seeping past shoulder 436 and/orcreating localized pressure increases at the tapered edges 408 and/orshoulder 436. This diminishment of pressure is important because duringpumping operations, the tapered edges 408 and/or the shoulder 436 act asload bearing surfaces and wear of these surfaces past a certain pointwill cause the closure element 420 to fail. Testing has shown that thepressure relief conduit 423 can reduce or relieve wear generated fromlocalized pressure acting on these surfaces and/or from fluid flowingdirectly over these surfaces. That is, the pressure relief conduit 423can allow fluid to flow freely past the seating section 438 and taperededges 408, which may reduce wear on the seating section 438 and/ortapered edges 408. The diminishment of pressure provided by pressurerelief conduit 423 may also help ensure that the closure element 420remains properly positioned in a fluid end segment. This is becausereducing the pressure acting on the bearing surfaces of the closureelement 420 (e.g., via interior surface 406 and/or tapered edges 408)will reduce the risk of pressure moving the closure element 420 out ofalignment in its segment and/or causing micromovements of the closureelement 420.

In the depicted embodiment, the closure element 420 includes a singlepressure relief conduit 423 that is generally aligned with a straightsection of the elongated ovular shape of the closure element 420.Additionally, the pressure relief conduit 423 is comprised of twostraight bores: one bore extending from the entrance 421 in a depthdimension of the closure element 420; and one bore extending from thefirst bore to the exit 422 along the narrow overall dimension 444 (seeFIG. 5 ) of the closure element 420. However, pressure relief conduit423 is merely an example and other embodiments may include one or morepressure relief conduits 423 of any dimension, shape, or form (e.g.,formed from any number of bores) positioned in any desirable location onthe closure element 420, provided that the pressure relief conduit 423provide pressure relief for wear/bearing surfaces of the closure element420. For example, pressure relief conduit 423 might comprise a diagonalbore extending directly from entrance 421 to exit 422. Additionally oralternatively, a closure element 420 might include two or more pressurerelief conduits 423 distributed evenly around the closure element 420(e.g., aligned with both straight sections of an overall elongated,ovular shape). Still further, in some embodiments, the fluid end mightdefine all or some of a pressure relief conduit, an example of which isdiscussed below in connection with FIG. 8H.

As one example of how the pressure relief conduit 423 may vary indifferent embodiments, FIGS. 8G and 8H depict a closure element 420′that is a slight variation of closure element 420. Closure element 420′includes pressure relief conduits 425 in the form of grooves on bothsides of the closure element 420′, e.g., in alignment with both straightsections of an elongated, ovular shape. While pressure relief conduits425 do not extend through the closure element 420 to create a flow paththat completely avoids the tapered edges 408 and the seating section438, the pressure relief conduits 425 serve a similar purpose andachieve the same advantages discussed above in connection with pressurerelief conduit 423. That is, the pressure relief conduits 425 helpreduce pressure on the closure element 420′, which reduces wear andhelps preserve or extend the lifespan of the closure element 420′.

To be clear, while the Figures described thus far depict a non-circularclosure assembly 400 as a plug-style closure assembly, the sameprinciples, structures, and/or features may also be applicable to asleeve-style/type closure element and could be used to close and/or sealother non-circular segments of a fluid end, such as a non-circularversion of segment 2226. That is, although not shown herein, asleeve-style, non-circular closure assembly 400 may extend betweencasing 206 and a packing arrangement. Thus, in some instances,non-circular closure assembly 400 disposed in segment 2226 may bereferred to as a packing sleeve. For the purposes of this application, asleeve- or plug-style closer element may be referred to as a stationaryclosure element. However, the techniques presented herein need not belimited to stationary closure elements and may also be used incombination with plungers or other movable closure elements, which, forthe purposes of this application, may be referred to as movable closureelements. That is, the non-circular concepts presented herein could alsobe applied to and/or utilized with packing elements.

More specifically, the concepts presented herein (e.g., in connectionwith closure assembly 400) may be applied to a packing arrangement and amovable closure element. That is, a sleeve-style, non-circular closureassembly may embodied as a packing arrangement and plunger. In suchinstances, the plunger 202 acts as a closure element and the packingacts as a seal element to form a sealing assembly for the closureassembly presented herein. To be clear, for the purposes of thisapplication, a sealing assembly formed from a packing arrangement andplunger may be referred to as a sealing assembly for a movable closureelement. By comparison, sealing assemblies embodied as plug-style orsleeve-style closure elements (with seal elements disposed around astationary closure element) may be referred to as sealing assemblies forstationary closure elements.

Now turning to FIGS. 6 and 7 , but with continued reference to FIG. 4 aswell, the non-circular segment 3224 is generally configured to mate withthe various portions of the closure assembly 400. In the depictedembodiment, this is achieved with a non-circular segment 3224 that isentirely non-circular. More specifically, the non-circular segment 3224includes an access section 320, a sealing section 330, and a seat 332that are each non-circular. In fact, the access section 320, the sealingsection 330, and the seat 332 of the depicted embodiment each have anelongated oval shape, matching the closure assembly.

However, to be clear, for the purposes of this application a fluid endsegment may be “non-circular” when one or more portions of the segmentis/are non-circular. For example, in some embodiments, the seat 332 maybe non-circular and the sealing section 330 and/or the access section320 may be circular. As a specific example, the access section 320 couldhave any shape provided that a radius (or major dimension) of the accesssection 320 is larger than the narrow overall dimension 444 of theclosure assembly 400. This will ensure that the closure assembly 400 canbe inserted through the sealing section 330 and into the seat 332 (orinto the pumping chamber 308, at least temporarily, as is explained infurther detail below). Meanwhile, the sealing section 330 can have anyshape configured to mate with the channel 434 of the closure assembly400 so that a seal 461 disposed in the channel 434 can seal against thesealing section 330.

Regardless of which sections of non-circular segment 3224 arenon-circular, overall, the non-circular segment 3224 is dimensioned toallow the closure assembly 400 to be inserted through the non-circularsegment 3224. More specifically, overall, the non-circular segment 3224includes a minimal narrow dimension 342 and a minimal elongateddimension 344. Each of these dimensions is configured to allow theclosure assembly 400 to be inserted through the non-circular segment3224 when the closure assembly 400 is disposed in an installationorientation O1 (see FIGS. 18A-18E).

To achieve this, the minimal narrow dimension 342 is larger than a depthof the closure assembly 400, or at least the depth of the closureelement 402 (insofar as “depth” is a dimension perpendicular to bothnarrow overall dimension 444 and elongated overall dimension 442).Meanwhile, the minimal elongated dimension 344 is larger than the narrowoverall dimension 444 of the closure assembly 400, or at least a narrowdimension of the closure element 402. Thus, when the narrow overalldimension 444 of the closure assembly 400 is aligned with the minimalelongated dimension 344 of the non-circular segment 3224 and the depthof the closure assembly 400 is aligned with the minimal narrow dimension342 non-circular segment 3224, the closure assembly 400 (or the closureelement 402) may be inserted through the non-circular segment 3224. Thatis, when the closure assembly 400 (or the closure element 402) is in aninstallation orientation O1, the closure assembly 400 (or the closureelement 402) may be inserted into and through the non-circular segment3224.

Another important aspect of the non-circular segment 3224 is its seat332. The seat 332 is configured to support the closure element 402 and,more specifically, to support the seating section 438 of the closureelement 402. At the same time, the seat 332 forms a fluid barrier thatis essentially in the pumping chamber 308 and, thus, the seat 332 mayexperience a large amount of wear. Accordingly, the seat 332 includescontoured edges 334 that are designed to smooth the transitions from thepumping chamber 308 and/or from the inlet segment 2126 to the seat 332and reduce or prevent wear on the casing 306. Notably, the contourededges 334 eliminate corners, which can be susceptible to wear, betweenthe inlet segment 2126, the pumping chamber 308, and the seat 332. Thismay be particularly important since the seat 332 may be hard to accessfor repairs.

Now turning to FIG. 8I, as mentioned above, in some embodiments, thenon-circular segment 3224 may also define one or more pressure relieffeatures. In some instances, such features may be defined entirely bythe fluid end 304, e.g., with holes or passages formed through thecasing 306 of the fluid end 304. In the depicted example, however, thepressure relief features 425′ are grooves formed in alignment with theminimal narrow dimension 342 of the non-circular segment 3224. Thesepassages may have a similar effect, and achieve similar advantages tothe pressure relief features 425 of FIGS. 8G and 8H. Additionally oralternatively, pressure relief features 425′ may enhance theeffectiveness of pressure relief features, such as pressure relieffeatures 425 of FIGS. 8G and 8H, included on and/or in a closureelement. Thus, in at least some instances, the non-circular segment 3224may—but need not—include pressure relief features 425′ when the closureelement includes corresponding pressure relief features.

Now turning to FIGS. 9-17 , these Figures generally depict variationsand/or modifications of a non-circular bore and/or a non-circularclosure assembly, as compared to the embodiments of FIGS. 3-8C. Forbrevity, the description of FIGS. 9-17 focuses on differences betweenthe embodiments and does not reiterate descriptions of like components.Instead, FIGS. 9-17 are labeled with like reference numerals whereapplicable and any description of like parts or components included inthis application should be understood to apply to like numbered parts.However, to be clear, the variations and modifications depicted in FIGS.9-17 should not be interpreted to limit the present application tocertain modifications or variations in any manner. Likewise, if acertain difference is not described in detail, this omission should notbe interpreted to require that certain parts, components or featuresmust be the same across different embodiments.

That all said, in FIG. 9 , a modified non-circular segment 3224′ isdepicted from a side, sectional view. As can be seen, the non-circularsegment 3224′ is substantially similar to non-circular segment 3224,except that the non-circular segment 3224 includes an access section 321that is counter-bored instead of tapered (like access section 320). Thiscounter-bored access section 321 may be advantageous because it mayprovide easier access to the sealing section 330 and/or seat 332, whichmay ease servicing and/or manufacturing. As mentioned, manufacturingnon-circular bores may be somewhat complicated and, thus, the accessafforded by access section 321 may be particularly advantageous for thetechniques presented herein.

Next, in FIG. 10 , the closure assembly 400″ is shaped substantiallysimilar to the closure assembly 400, but is now only formed from aclosure element 402′. That is, closure assembly 400″ includes a closureelement 402′ that is self-retaining and does not include a retainingassembly (like retaining assembly 470). To compensate for this, theclosure element 402′ includes an exterior surface 410′ with a radialsurface 411 that extends radially beyond the closure section 430. Thus,channel 434′ is defined between the shoulder 436 and the radial surface411 of the exterior surface 410′.

One other notable difference is that the closure element 402′ includesinstallation elements 450 extending outwardly, away from the exteriorsurface 410′. The installation elements 450 provide a grip point on theexterior surface 410′ that can be used during installation and/orremoval of the closure element 402 from a non-circular segment 3224(e.g., like flexible installation elements 485). In the depictedembodiment, the installation elements 450 comprise two U-shaped barsthat extend along the narrow overall dimension 444 of the closureelement 402′, on either side of a central bore 416′. However, in otherembodiments, the installation elements 450 may have any shape and/or mayextend in any direction, across any portion of the exterior surface410′. But, at the same time, it may be beneficial to arrange theinstallation elements 450 symmetrically and/or evenly with respect to acenter of the exterior surface 410 (e.g., around and/or with respect tobore 416′ because symmetrically or evenly spaced installation elements450 may allow for linear translation that avoids tilting or rotation.The bore 416′ may also be helpful for installation, removal, and/orsecuring the closure element 402′ within a non-circular segment 3224.

FIGS. 11A and 11B depict yet another embodiment of the non-circularclosure assembly presented herein. In this embodiment, the closureassembly 500 includes the closure element 402 and the retaining element472 of FIGS. 3-8A, but now the retaining assembly 470 also includes acrossbar 502 and an extended coupler 504. As can be seen in FIG. 11A,the crossbar 502 extends across the non-circular segment 3224 (e.g.,across the access section 320), so that the crossbar 502 can sit outsidethe external surface 310 of the casing 306. Then, the crossbar 502 cansupport an extended coupler 504 that stretches from the external surface310 to the closure element 402. Thus, the crossbar 502 and extendedcoupler 504 can further secure the closure element 402 in place in thenon-circular segment 3224 (e.g., on a seat 332) and, among otheradvantages, prevent the closure element 402 from being pushed into orsucked out of the non-circular segment 3224 (or more specifically of theseat 332).

FIGS. 12A and 12B depict a closure assembly 500′ that is a variant ofthe closure assembly 500 of FIGS. 11A and 11B; but now the closureassembly 500′ incorporates retaining assembly 470′ of FIGS. 8B and 8C.Also, the embodiment of FIGS. 12A and 12B includes certain advantageousfeatures, including: (1) a collar 505 disposed on an upstream end of theextended coupler 504; (2) handle extensions 506 that extend from adownstream end of the extended coupler 504; and (3) a crossbar 502 witha slightly modified geometry. Each of these features may help keep theclosure element 402 stable during pumping operations (e.g., duringfracking or drilling operations) and/or may help ensure that the closureelement 402 is properly installed into the fluid end 304. Testing hasrevealed that a misalignment between the closure element 402 and itsnon-circular segment 3224 can lead to micromovements (or largermovements if the misalignment is more pronounced) that cause gallingdamage of the fluid end 304 that is detrimental to lifespan and/ordifficult to repair. Thus, it is important to install a closure element402 in a non-circular segment 3224 in an aligned position and tomaintain the closure element 402 in such a position during pumpingoperations.

The collar 505 and the extensions 506 may both help prevent ordiscourage a user from improperly installing the non-circular closureelement 402, e.g., in a manner that damages the closure element 402.First, the collar 505 may allow the extended coupler 504 to be coupledto the retaining element 472′ and/or closure element 402 (e.g., viathreading), but may limit the depth the extended coupler 504 can extendinto the retaining element 472′ and/or closure element 402. This mayprevent the extended coupler 504 from damaging the closure element 402during installation. Meanwhile, the extensions 506 may prevent, or atleast discourage, a user from engaging the hex-shaped head of theextended coupler 504 with impact drills or other such torquing tools todrive installation of the extended coupler 504 during installation ofclosure assembly 500′. This may discourage a user from over-torquing theextended coupler 504 and damaging closure element 402.

The crossbar 502 may include a slot 503 extending inwards from a side ofthe crossbar 502 and may include stepped inner surfaces 508 at its topand bottom end. The side slot 503 may ease installation while stillensuring that the crossbar 502 securely supports the extended coupler504. Meanwhile, the stepped inner surfaces 508 may help securely seatthe crossbar 502 in the non-circular segment 3224 and against theexternal surface 310 of the fluid end 304. Or, in other embodiments,stepped inner surfaces 508 may help securely seat the crossbar 502 on aretainer (see, e.g., the retainer 602 of FIG. 16 ) coupled to anexternal surface 310 of the fluid end 304. In any case, stepped innersurfaces 508 may help the crossbar 502 securely support the closureelement 402 during installation and during pumping operations of thefluid end 304 (e.g., during fracking or drilling).

FIGS. 13-15 depict an embodiment that is similar to the embodiments ofFIGS. 11A, 11B, 12A, and 12B; however, now closure assembly 600 includesretaining assembly with a crossbar 502′ and extended coupler 504′ thatare supported by a retainer 602 in the form of an annular ring on theexternal surface 310 of the casing 306 (i.e., disposed exteriorly ofcasing 306). The retainer 602 extends from an interior surface 606 to anexterior surface 608. The interior surface 606 abuts the externalsurface 310 of casing 306 when the retainer 602 is installed thereon.Additionally, in the depicted embodiment the retainer 602 is an annularring so that it extends from an internal surface 604 that surroundsand/or defines the exterior opening of the non-circular segment 3224″ toan external surface 610.

More specifically, in the depicted embodiment, both the internal surface604 and the external surface 610 are non-circular. However, in otherembodiments, the retainer 602 need not include a non-circular internalsurface 604 and a non-circular external surface 610. For example, theexternal surface 610 might be circular or the overall retainer 602 mighthave any desirable shape that can secure the crossbar 502′ to theexternal surface 310. The key, for at least some embodiments, is thatthe internal surface 604 extends at least partially over/within theexterior opening of the non-circular segment 3224″ so that the interiorsurface 606 can define a shoulder at a proximal end of the non-circularsegment 3224″. In the embodiment depicted in FIGS. 13-15 , thenon-circular segment 3224″ has substantially constant dimensions (e.g.,a single non-circular shape) and, thus, the interior surface 606 may besized based off of a single non-circular shape. However, thisnon-circular segment 3224″ is merely an example provided for simplicityand, in other embodiments, the retainer 602 can be used with anydesirable non-circular segment. For example, in other embodiments, theretainer 602 may be sized to mate with, and extend partially over, aproximal end of an access section of a non-circular bore (e.g., accesssection 320 or 321).

Additionally, in the embodiment of FIGS. 13-15 , the closure assembly600 includes a closure element 402″ that does not include a fullybounded seal channel (e.g., like channel 434). Instead, closure element402″ defines a channel 434′ that is defined by the closure section 430,bounded on an upstream side by the seating section 438, and open on adownstream side. Then, as can be seen best in FIG. 15 , a seal carrier660 extends between the interior surface 606 of the retainer 602 and theshoulder 436 of the closure element 402″ to support a seal 461 betweenthe closure element 402″ and the non-circular segment 3224″. Indifferent embodiments, the seal carrier 660 may support the seal 461 inany desirable location between the shoulder 436 and the interior surface606 of the retainer 602.

FIGS. 16A and 16B depict another embodiment that utilizes a retainer 602as part of the retaining assembly; however, now, the closure assembly700 includes a closure element 402′″ that is secured adjacent theexternal surface 310 of the casing 306. One notable advantage of thisembodiment is that the closure element 402′″ is configured to sealagainst the retainer 602 and, thus, any wear from this seal occurs on areplaceable part (retainer 602). More specifically, the closure element402′″ resembles the self-retaining closure element 402′ of FIG. 10 , butwithout the installation elements 450, and thus, defines channel 434′between its seating section 438 and its exterior surface 410. Meanwhile,the retainer 602 is configured to extend at least partially within thelateral bounds of the non-circular segment 3224″ so that the channel434′ can sit against the internal surface 604 of the retainer 602,sealing there against.

In still other embodiments, however, the closure element 402″ need notdefine the channel 434′ and, for example, the channel 434′ could bedefined by the retainer 602. That is, the retainer 602 might define achannel for a seal assembly 460 which could transfer wear to the closureelement 402″. This might increase the lifespan of the retainer 602,reducing the number of times that the retainer 602 needs to be removedor serviced during pumping operations. Notably, removing the retainer602 from the fluid end 304 requires multiple bolts/couplers to beremoved. By comparison, the closure element 402″ might be able to beremoved from the fluid end 304 without removing any bolts/couplers.Thus, it might be easier and/or quicker to service or replace theclosure element 402″ than the retainer 602. That is, moving the channel434′ to the retainer 602 might provide servicing advantages (e.g., lessdown time). One example of such a channel is depicted in FIG. 17B.

More specifically, the seating section 438 of the closure element 402′″may sit against the interior surface 606 of the retainer 602, which maysecure/retain the closure element 402′″ within the non-circular segment3224″ when the closure element 402′″ is disposed in an operationorientation O2. At least because the closure element 402″ is securedwithin the non-circular segment 3224″ adjacent the external surface 310(and the retainer 602), the coupler 504″ need not be extended. This mayalso be advantageous because it may reduce the chances that the coupler504 experiences stresses or torques (e.g., due to misalignment). Also,to be clear, this embodiment is again depicted with a relativelystraight/constant, non-circular segment 3224″, but the non-circularsegment 3224″ is, again, only provided as a example and the concepts ofthis embodiment need not be limited to such bores.

FIGS. 17A and 17B depict yet another embodiment of a closure assembly701 that utilizes a retainer 603 as part of the retaining assembly;however, now, the retainer 603 is provided in the form of a plate (asopposed to a ring, like retainer 602). Aside from its shape, theretainer 603 is similar to retainer 602. For example, retainer 603extends from an interior surface 606 that abuts the external surface 310of the casing 306 to an exterior surface 608 and also extends frominternal surfaces 604 (which define holes 609) to an external surface610 that defines a radial boundary of the retainer 603. In the depictedembodiment, the retainer 603 covers multiple non-circular segments 3224″and provides separate holes 609 for each of these segments. Thus, theretainer 603 includes multiple, disconnected and discrete internalsurfaces 604. In other embodiments, however, a single internal surface604 might span multiple non-circular segments 3224″ or a retainer 603might only span a single bore segment.

Moreover, in FIGS. 17A and 17B, the closure assembly 701 includes aclosure element that is substantially similar to closure element 402′″and, thus, the closure element is labeled with like numerals. Theclosure element 402′″ is again (as compared to FIGS. 16A and 16B)secured adjacent the external surface 310 of the casing 306 and thus,realizes similar advantages, but as mentioned above, does not includechannel 434′. Instead, the channel 434′ is provided in the casing 306and/or the retainer 603 to achieve the advantages discussed above. Stillfurther, in FIGS. 17A and 17B, the closure element 402′″ is shownretained in the fluid end 304 by the retainer 603 alone. While this isone option, further components, such as a crossbar and an extendedcoupler might also be used in combination with retainer 603 if desired.

Now turning to FIGS. 18A-18E, these Figures diagrammatically depict amethod of closing an externally open segment of a fluid end of areciprocating pump with a closure assembly. Initially, as is shown inFIG. 18A, a first step 802 involves orienting a closure element 402 inan installation orientation O1 and arranging the closure element 402 forinsertion into a non-circular segment 3224. As mentioned, in at leastsome embodiment, the installation orientation O1 aligns a depth of theclosure element 402 with a narrow dimension of the non-circular segment3224 and aligns a narrow dimension of the closure element 402 with anenlarged dimension of the non-circular segment 3224. Thus, onceorientated in the installation orientation O1, the closure element 402can be translated along a lateral axis A1 in a first lateral directionD1. This translational movement moves the closure element 402 throughthe non-circular segment 3224, from the external surface 310 of thecasing 306 to the pumping chamber 308 of the casing 306.

In a second step, the closure element 402 is rotated from itsinstallation orientation O1 to an operational orientation O2 that isangularly offset from the installation orientation O1. For simplicity,this step is depicted in two sub-steps: sub-step 804(1) and sub-step804(2); however, in other embodiments, this step can be accomplished inone or more operations. For example, the closure element 402 may berotated about two axes at one time. That said, in FIGS. 18B and 18C, tworotations are shown.

First, in sub-step 804(1), the closure element 402 is rotated aboutlateral axis A1 in a first rotational direction D2. For example, theclosure element 402 may rotate approximately ninety degrees. This mayalign the narrow dimension of the closure element 402 with the narrowdimension of the non-circular segment 3224 and, thus, in at least someembodiments, it might not be easy to remove the closure element 402 fromthe pumping chamber 308 via the non-circular segment 3224 after thisfirst rotation. But, since the depth of the closure element 402 may nowbe aligned with the enlarged dimension of the non-circular segment 3224,it may still be possible to remove the closure element 402 from thepumping chamber 308.

Then, in sub-step 804(2), the closure element 402 is rotated about depthaxis A3 in second rotational direction D3. For example, the closureelement 402 may rotate approximately ninety degrees. This rotates theenlarged dimension of the closure element 402 into alignment with theenlarged dimension of the non-circular segment 3224 and, thus, orientsthe closure element 402 for seating in the non-circular segment 3224.That is, after rotating the closure element 402 about two axes, theclosure element 402 may be disposed in an operational orientation O2.

Next, in step 806, the closure element 402 is translated is translatedalong lateral axis A1 in a second lateral direction D4, as is shown inFIG. 18D. The second lateral direction D4 is opposite to the firstlateral direction D1 and, thus, this translation moves the closureelement 402 towards and/or further into the non-circular segment 3224,causing the closure element 402 to seat in the non-circular segment3224, eventually moving into installation position P1 (see FIG. 18E).The final seating may also require some lateral adjustments along alongitudinal axis A2, depending on the position of the closure element402 after the rotation(s).

Notably, in FIGS. 18A-18E, the closure element 402 is installed byitself. In some embodiments (e.g., the embodiment of FIG. 10 ), theclosure element 402 may be able to retain a seal on its own and, thus,may define an assembly 401 without any further components. This sealingassembly 401 may also be self-retaining (e.g., like the embodiment ofFIG. 10 ) and, thus, installation of the closure assembly 400 may, insome instances, be complete after step 806. However, in otherembodiments, the closure assembly 400 may include a retaining assembly470 that secures and/or retains the closure element 402 and/or a seal461 within the non-circular segment 3224. For example, step 808 mayinvolve installing a seal 461 and/or a retaining assembly 470 onto aclosure element 402 positioned/seated in the installation position P1 tosecure the closure element 402 within the 3224. Alternatively, any ofthe other retaining assemblies depicted herein, or variations thereof,might be installed on a fluid end casing after the sure element 402positioned/seated in the installation position P1.

Still further, some components of a closure assembly formed inaccordance with the present application might be installed prior tocompleting the method of FIGS. 18A-18E. For example, an annular ring(e.g., retainer 602) might be installed on external surface 310 and leftin place before installation and subsequent to removal of a closureelement, if desired. In some embodiments, this could reduce downtimeduring servicing if, for example, the annular ring includes a largenumber of couplers while the closure element 402 can be installed orremoved without removing any couplers (or a single extended coupler504). To be clear, the installation process may be suitable for, or canbe slightly modified for, any embodiment, variation, or modificationpresented herein. For example, in FIGS. 18A-18E, the part labeled asclosure element 402 may be closure assembly that comprises a retainingelement 472 and a closure element 402. These two parts may be coupledtogether prior to step 802, e.g., to capture a seal assembly 460. Then,the closure assembly (or this portion of the closure assembly) may beinserted into the fluid end 304, rotated, and translated, e.g., inaccordance with the method of FIGS. 18A-18E.

FIG. 19 provides a specific example of how, in some embodiments, atleast some of the method of FIGS. 18A-18E might be completed by way ofadditional features. First, some steps might be completed bymanipulating the closure element 402, with or without retaining element472 (as well as any seal 461 and/or seal carrier 462 retained therein),with flexible handles 485. As mentioned, hand positioning the closureelement 402 in the non-circular segment 3224 by way of flexibleinstallation elements 485 may help properly position the closure element402 in alignment with a seat of the non-circular segment 3224. Also,before, after, or during step 806 of the method of FIGS. 18A-18E, anextended coupler 504 may coupled to a retaining element 472, as isgenerally depicted in FIG. 19 . The extended coupler 504 is thenretained by a crossbar 502, e.g., at step 810. As mentioned inconnection with FIGS. 12A and 12B above, in some instances a collar 505of the extended coupler 504 and/or handle extensions 506 of the extendedcoupler 504 may prevent, or at least discourage, a user fromover-torquing the extended coupler 504. In turn, this may preventmisalignment of the closure element 402 in the non-circular segment3224. The extended coupler 504 might also pull or “suck” the closureassembly into a proper seating alignment.

While the invention has been illustrated and described in detail andwith reference to specific embodiments thereof, it is nevertheless notintended to be limited to the details shown, since it will be apparentthat various modifications and structural changes may be made thereinwithout departing from the scope of the inventions and within the scopeand range of equivalents of the claims. In addition, various featuresfrom one of the embodiments may be incorporated into another of theembodiments. For example, a retainer, such as a retaining ring, or anyother component of a retaining assembly shown with one embodiment of aclosure element can be used with any desirable closure element to formaclosure assembly of the present application. Accordingly, it isappropriate that the appended claims be construed broadly and in amanner consistent with the scope of the disclosure as set forth in thefollowing claims.

It is also to be understood that the sealing assembly described herein,or portions thereof may be fabricated from any commonly used sealmaterials, such as homogeneous elastomers, filled elastomers, partiallyfabric reinforced elastomers, and full fabric reinforced elastomers.Suitable resilient elastomeric materials includes, but re not limitedto, thermoplastic polyurethane (TPU), thermoplastic copolyester (COPE),ethylene propylene diene monomer (EPDM), highly saturated nitrile rubber(HNBR), reinforced versions of the foregoing materials, such as versionsreinforced with fibers or laminations of woven material, as well ascombinations of any of the foregoing materials.

Similarly, it is intended that the present invention cover themodifications and variations of this invention that come within thescope of the appended claims and their equivalents. For example, it isto be understood that terms such as “left,” “right,” “top,” “bottom,”“front,” “rear,” “side,” “height,” “length,” “width,” “upper,” “lower,”“interior,” “exterior,” “inner,” “outer” and the like as may be usedherein, merely describe points of reference and do not limit the presentinvention to any particular orientation or configuration. Further, theterm “exemplary” is used herein to describe an example or illustration.Any embodiment described herein as exemplary is not to be construed as apreferred or advantageous embodiment, but rather as one example orillustration of a possible embodiment of the invention.

Finally, when used herein, the term “comprises” and its derivations(such as “comprising”, etc.) should not be understood in an excludingsense, that is, these terms should not be interpreted as excluding thepossibility that what is described and defined may include furtherelements, steps, etc. Meanwhile, when used herein, the term“approximately” and terms of its family (such as “approximate,” etc.)should be understood as indicating values very near to those whichaccompany the aforementioned term. That is to say, a deviation withinreasonable limits from an exact value should be accepted, because askilled person in the art will understand that such a deviation from thevalues indicated is inevitable due to measurement inaccuracies, etc. Thesame applies to the terms “about” and “around” and “substantially.”

1. A closure element for a fluid end of a reciprocating pump, the closure element being installable within a segment of a casing of the fluid end to substantially close the segment, the closure element comprising: a main body that extends from an interior surface to an exterior surface, wherein at least a portion of the main body has a non-circular cross-sectional shape.
 2. The closure element of claim 1, wherein the non-circular cross-sectional shape is an extended ovular shape.
 3. The closure element of claim 1, wherein the main body comprises: a seating section proximate the interior surface; and a closure section proximate the exterior surface.
 4. The closure element of claim 3, wherein the seating section extends radially beyond the closure section.
 5. The closure element of claim 4, wherein the seating section has a first non-circular cross-sectional shape and the closure section has a second non-circular cross-sectional shape that is smaller than the first non-circular cross-sectional shape.
 6. The closure element of claim 4, wherein only one of the seating section and the closure section includes the non-circular cross-sectional shape.
 7. The closure element of claim 4, wherein the seating section defines a non-circular shoulder between the seating section and the closure section.
 8. The closure element of claim 7, wherein the closure section defines a seal channel adjacent or proximate to the non-circular shoulder.
 9. The closure element of claim 3, further comprising: one or more pressure relief conduits configured to allow fluid to bypass the seating section of the main body and flow to the closure section of the main body.
 10. The closure element of claim 9, wherein the non-circular cross-sectional shape is an extended ovular shape and the one or more pressure relief conduits are aligned with one or more straight portions of the extended ovular shape.
 11. The closure element of claim 1, further comprising: one or more installation elements extending away from the exterior surface so that that the one or more installation elements are accessible from an exterior of the segment of the casing of the fluid end when the closure element is installed within the segment.
 12. A closure assembly formed with the closure element of claim 1, the closure assembly further comprising: a retaining assembly that is coupleable to the exterior surface of the closure element.
 13. The closure assembly of claim 12, wherein the retaining assembly is configured to be disposed entirely within the segment of the casing of the fluid end when the closure element is installed within the segment of the casing of the fluid end to substantially close the segment.
 14. The closure assembly of claim 12, wherein at least a portion of the retaining assembly is configured to be disposed at least partially exteriorly of the casing of the fluid end when the closure element is installed within the segment of the casing of the fluid end to substantially close the segment.
 15. A closure assembly for a fluid end of a reciprocating pump, at least a portion of the closure assembly being installable within a segment of a casing of the fluid end to substantially close the segment, the closure assembly comprising: a closure element that extends from an interior surface to an exterior surface, wherein at least a portion of the closure element has a non-circular cross-sectional shape; a retaining element that is coupleable to the exterior surface of the closure element; and a seal assembly that is positionable between the closure element and the retaining element, proximate the closure element, wherein coupling the retaining element to the closure element retains the seal assembly therebetween.
 16. The closure assembly of claim 15, wherein the closure element has a first surface hardness, the retaining element has a second surface hardness, and the first surface hardness is different than the second surface hardness.
 17. The closure assembly of claim 15, wherein the seal assembly comprises a seal and a single seal carrier, the seal being proximate the closure element and the single seal carrier being positioned between the seal and the retaining element.
 18. The closure assembly of claim 15, wherein the retaining element is part of a retaining assembly that further comprises: a crossbar configured to span the segment proximate an exterior end of the segment; and an extended coupler, wherein an upstream end of the extended coupler is configured to be coupled to the retaining element and a downstream end of the extended coupler is configured to be secured to the crossbar.
 19. The closure assembly of claim 15, wherein the retaining element comprises one or more installation elements extending away from an exterior surface of the retaining element so that that the one or more installation elements are accessible from an exterior of the segment of the casing of the fluid end when the closure element is installed within the segment.
 20. The closure assembly of claim 15, wherein the retaining element is part of a retaining assembly that further comprises: a retainer disposed exteriorly of the casing of the fluid end and defining one or more seats on which the closure element, a portion of the retaining assembly, or both the closure element and the portion of the retaining assembly may sit. 